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## Defines concept of the mole as a counting unit

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Amedeo Avogadro provided the unit of measurement called the mole (mol), or the amount of a substance that contains 6.02 x 1023 particles of that substance. How many water molecules are in a mole of water molecules?

Avogadro's number (6.02 x 1023) is the number of representative particles in a mole. What is a representative particle? Can molecules be representative particles?

#### Conversions Between Moles and Atoms

You can use dimensional analysis to convert moles to particles and vice versa.

Remember: 1 mole = 6.02 x 1023 atoms or particles.

Two water molecules contain 4 hydrogen atoms and 2 oxygen atoms. A mole of water molecules contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms. [Figure1]

How many moles of helium atoms is 4.72 x 1024 atoms of helium?

How many hydrogen atoms are in a mole of water (H2O) molecules? How many oxygen atoms?